Method for producing non-grain oriented electric sheet steel

ABSTRACT

The present invention relates to a method for producing non grain-oriented magnetic steel sheets in which hot strip is produced from an input stock such as cast slabs, strip, roughed strip, or thin slabs, made of steel comprising (in weight %) C: 0.001-0.05%; Si: ≦1.5%; Al: ≦0.4% with Si+2Al≦1.7%; Mn: 0.1-1.2%; if necessary up to a total of 1.5% of alloying additions such as P, Sn, Sb, Zr, V, Ti, N, Ni, Co, Nb and/or B; with the remainder being iron as well as the usual accompanying elements; in that the input stock is hot-rolled directly from the casting heat or after preceding reheating to a reheating temperature between min. 1000° C. and max. 1180° C. in several deformation passes, and subsequently coiled, wherein during hot-rolling at least the first deformation pass takes place in the austenitic region and at least one further deformation pass takes place in the two-phase mixing region austenite/ferrite, and wherein during rolling in the two-phase mixing region a total deformation ε h  of at least 35% is achieved.

BACKGROUND OF THE INVENTION

The invention relates to a method for producing non grain-orientedmagnetic steel sheets in which hot strip is produced from an input stockmade of steel, such as cast slabs, strip, roughed strip, or thin slabs,wherein the magnetic steel sheets have little hysteresis loss and highpolarisation, as well as good mechanical properties. Such nongrain-oriented magnetic steel sheets are predominantly used as corematerial in electrical machinery such as motors and generators with arotating direction of magnetic flux.

In this document the term “non grain-oriented magnetic steel sheets”refers to magnetic steel sheets covered by DIN EN 10106 (“magnetic steelsheets subjected to final annealing”) and DIN EN 10165 (“magnetic steelsheets not subjected to final annealing”). Furthermore, more stronglyanisotropic types are also included provided they are not deemed to fallinto the category of grain-oriented magnetic sheets.

The processing industry demands non grain-oriented magnetic steel sheetswhose magnetic properties are better than those of conventional sheetsof this type. There is a demand for reduced hysteresis loss coupled withan increased polarisation in the particular induction range used. At thesame time, the respective treatment and processing steps to which themagnetic steel sheets are subjected in the context of their use, placespecial demands on the mechanical/technological characteristics of saidmagnetic steel sheets. In this context, cuttability of the sheets, e.g.during stamping, assumes particular importance.

By increasing magnetic polarisation, the magnetisation requirement isreduced. At the same time, copper losses are reduced too, said copperlosses forming a significant part of the losses which arise during theoperation of electrical machinery. The economic value of nongrain-oriented magnetic steel sheets with increased permeability is thusvery considerable.

The demand for types of non grain-oriented magnetic steel sheets whichhave greater permeability, not only relates to non grain-orientedmagnetic steel sheets with high losses (P1.5≧5−6 W/kg), but also sheetswith medium losses (3.5 W/kg≦P1.5≦5.5 W/kg) and low losses (P1.2≦3.5).This is the reason for efforts to improve the entire spectrum of themagnetic polarisation values of lightly siliconised, medium-siliconisedand highly siliconised electrotechnical steels.

One approach to producing magnetic steel sheets of increasedpermeability, said approach being based on medium-siliconised or lightlysiliconised alloys, consists of subjecting the hot strip to hot stripannealing during production. Thus for example WO 96/00306 proposes thathot strip intended for the production of magnetic steel sheets, befinish-rolled in the austenitic region, and that coiling be undertakenat temperatures above the complete transformation to ferrite. Inaddition, annealing of the coil takes place directly from the rollingheat. In this way a final product with good magnetic characteristics isobtained. However, due to the high energy requirements for heatingbefore and after hot-rolling as well as due to the required alloyingadditions, the associated increased costs have to be accepted.

According to EP 0 469 980 an increased coiling temperature incombination with an additional hot strip annealing should be aimed for,so as to obtain useful magnetic characteristics even with low alloyingcontents. This too can only be accomplished if the increased costs areaccepted.

SUMMARY OF THE INVENTION

It is thus the object of the invention to provide an economical way ofproducing magnetic steel sheets with improved characteristics.

According to the invention, this object is met by a method for producingnon grain-oriented magnetic steel sheets in which, starting with aninput stock such as cast slabs, strip or thin slabs made from a steelcomprising (in weight %) 0.001-0.05% C, ≦1.5% Si, ≦0.4% Al, withSi+2Al≦1.7%, 0.1-1.2% Mn, if necessary up to a total of 1.5% alloyingadditions such as P, Sn, Sb, Zr, V, Ti, N, Ni, Co, Nb and/or B, with theremainder being iron as well as the usual accompanying elements, a hotstrip is produced in that the input stock is hot-rolled directly fromthe casting heat or after preceding reheating to a reheating temperaturebetween min. 1000° C. and max. 1180° C. in several deformation passes,and subsequently coiled, wherein during hot-rolling at least the firstdeformation pass takes place in the austenitic region and at least onefurther deformation pass takes place in the two-phase mixing regionaustenite/ferrite, and wherein during rolling in the two-phase mixingregion a total deformation ε_(h) of at least 35% is achieved.

According to the invention, the magnetic characteristics of magneticsteel sheets are influenced in a targeted way by deformation during theindividual deformation passes undertaken during hot-rolling, dependingon the respective microstructural condition at the time. Rolling in thetwo-phase mixing region is to be a decisive component; by contrast, thecomponent of deformation in the ferritic region should be kept as smallas possible. Thus the method according to the invention is particularlysuitable for processing those Fe—Si alloys that have a pronouncedtwo-phase mixing region between the austenitic and the ferritic region.

Attuning the alloying additions of ferrite-forming and austenite-formingelements, taking into account the contents range according to theinvention of the individual elements, is to be undertaken starting witha base composition of (Si+2Al)≦1.7, namely such that there is anadequate distinction of the two-phase mixing region.

If cast slabs are used as an input stock, they are reheated to atemperature ≧1000° C. so that the material is completely in theaustenitic state. For the same reason, cast thin slabs or cast stripare/is used directly exploiting the casting heat and if necessary areheated up to an initial rolling temperature exceeding 1000° C. Therequired reheating temperature increases in line with an increase in theSi content, but an upper limit of 1180° C. is not to be exceeded.

As a rule, hot-rolling according to the invention is carried out in afinish-rolling line comprising several roll stands. The purpose ofrolling in the austenitic region which takes place in a single pass orin several passes, consists of being able to carry out the transitionfrom the austenitic region to the two-phase mixing region and from thetwo-phase mixing region to the ferritic region in a controlled waywithin the finish-rolling line. The deformation passes carried out inthe austenitic region also serve the purpose of setting the thickness ofthe hot strip prior to the start of rolling in the two-phase mixingregion so that the desired total deformation taking place during rollingin the two-phase mixing region (“mixing rolling”) is safely attained.Mixing rolling also involves at least one deformation pass. Preferablyhowever, several deformation passes are carried out in the mixing regionaustenite/ferrite, so as to safely achieve the total deformation of atleast 35% required during such mixing rolling, thus obtaining thedesired setting of the microstructure of the hot strip.

The term “total deformation ε_(h)” refers to the ratio of thicknessreduction during rolling in the respective phase region to the thicknessof the strip when it enters the respective phase region. According tothis definition, the thickness of hot strip produced according to theinvention, for example after rolling in the austenitic region, is h₀.During subsequent rolling in the two-phase mixing region, the thicknessof the hot strip is reduced to h₁. According to the definition, thisresults for example, in a total deformation ε_(h) attained during mixingrolling to (h₀-h₁)/h₀ with h₀=thickness during entry into the first rollstand which is passed in the mixing state austenite/ferrite, andh₁=thickness when leaving the last roll stand in the mixing state.

According to the invention, the total deformation ε_(h) during rollingin the two-phase mixing region austenite/ferrite is to amount to atleast 35%, so as to set or prepare for the subsequent process steps acondition of the hot-rolled strip concerning grain size, texture andprecipitations, which condition favours the desired magnetic andtechnological characteristics. Ideal processing results can be achievedif the total deformation in the two-phase mixing regionaustenite/ferrite is limited to max. 60%.

By hot-rolling, which predominantly is a mixing rolling, avoidingrolling in the ferritic region as far as possible, a hot strip can beproduced which can subsequently be used for the production of magneticsteel sheets and for the production of components with outstandingmagnetic characteristics. To this effect, no additional process steps orthe need to maintain certain elevated temperatures during hot-rolling,are required. Instead, by implementing a rolling strategy which isoptimised both in regard to temperature management and in regard tostaggering the deformation passes, in conjunction with a suitablecoiling temperature, the method according to the invention makes itpossible to economically produce a high-quality magnetic steel sheetmaterial.

It has been shown that merely combining the measures according to theinvention with maintaining the range of deformation of 35% to 60% fordeformation in the mixing region austenite/ferrite, as provided by theinvention, magnetic steel sheets can be produced whose characteristicsmatch those of magnetic steel sheets produced in a conventional waywhich in addition have passed through time-consuming and expensiveprocess steps such as supplementary hot-strip annealing. Furthermore ithas been shown that in cases where hot-strip annealing is carried out tosupplement the method according to the invention, the combined effect ofsuch measures leads to magnetic steel sheets which in their magnetic andmechanical characteristics are superior to magnetic steel sheets made inthe traditional way. Thus the invention results in a significantreduction of costs for producing high-quality magnetic steel sheets.Furthermore, based on the method according to the invention, sheets canbe produced whose characteristics are far superior to those ofconventionally produced magnetic steel sheets.

An advantageous embodiment of the invention is characterised in that thehot strip after deformation in the austenitic region is exclusivelyfinish-rolled in the two-phase mixing region austenite/ferrite. Inparticular, with this variant of the invention, the total deformationε_(h) achieved during rolling in the two-phase mixing regionaustenite/ferrite should be at least 50%. With this variant of themethod according to the invention, rolling in the ferritic state of thehot strip is completely avoided. Strip made on the basis of Fe—Sisteels, which have a pronounced two-phase mixing regionaustenite/ferrite at the transition from austenite to ferrite, areparticularly suited to this sequence of rolling steps where there is norolling in the ferritic region. Optimal temperature management in thesense of preventing cooling of the material to be rolled can be achievedand thus complete transformation to ferrite can be prevented by asuitable selection of the ratio of degree of transformation and speed oftransformation, i.e. by utilising the heat generated during deformation.

According to an alternative variant of the process according to theinvention, following rolling in the two-phase mixing regionaustenite/ferrite, at least one deformation pass is carried out in theferritic region.

The total deformation ε_(h) achieved during rolling in the ferriticregion should be at least 10% and at most 33%. With this embodiment ofthe invention too, rolling in the ferritic region is reduced to aminimum so that the emphasis of deformation remains in the mixing regionof austenite/ferrite in spite of final rolling being in the ferriticregion.

In principle, a coiling temperature of at least 700° C. is suitable forcarrying out the method according to the invention. If this coilingtemperature is maintained, hot-strip annealing can be done withoutentirely or at least to a substantial degree. The hot strip is alreadysoftened in the coil; this has a positive influence on the parameterswhich determine its characteristics, e.g. on grain size, texture andprecipitation. In this context it is particularly advantageous if thecoiled hot strip from the coiling heat is subjected to direct annealingand if the annealing time at an annealing temperature exceeding 700° C.is at least 15 minutes. Such in-line annealing of the hot strip which iscoiled at high temperature and which is not significantly cooled down inthe coil, can completely replace hot-strip batch-type annealing whichmay otherwise be required. Thus annealed hot strip with particularlygood magnetic and technological characteristics can be produced. Theexpense in time and energy is considerably reduced when compared tohot-strip annealing which is conventionally carried out to improve thecharacteristics of magnetic steel sheets.

According to an embodiment of the invention which is particularlysuitable for processing a steel with an Si content of at least 0.7weight %, following rolling in the finish-rolling line, the hot strip iscoiled at a coiling temperature of less than 600° C., in particular lessthan 550° C. With the respective alloys, coiling at these temperaturesresults in a strengthened hot-strip condition.

Preferably at least one of the last deformation passes in the ferriticregion is carried out by hot-rolling with the use of lubricant.Hot-rolling with lubricant results in reduced shear deformation so thatthe structure of the rolled strip is more homogeneous across itscross-section. Furthermore, lubrication reduces the rolling forces sothat a greater thickness reduction becomes possible for a given rollpass. Depending on the desired characteristics of the magnetic steelsheets to be produced it can therefore be advantageous if alldeformation passes taking place in the ferritic region are carried outwith roll lubrication.

Irrespective of the sequence of rolling steps selected in a particularcase, further improvement in the characteristics of the magnetic steelstrip produced can be achieved in that, following coiling and cooling,the hot strip is additionally annealed at an annealing temperature of atleast 740° C. This annealing can be carried out in a batch-typeannealing furnace or in a continuous furnace. In particular, if castthin slabs or cast strip are/is used as an input stock, hot strip with athickness of ≦1.5 mm can be produced. In this context, strip ofparticularly high quality can be produced in that the cast input stockis produced in a casting and rolling plant and emanating from it, isdirectly fed to the roll train.

The characteristics of hot strip produced according to the invention areso good that for a multitude of applications the strip can be useddirectly as magnetic steel sheets without the need for renewedcold-rolling where cold working beyond smoothing or dressing is carriedout. Thus in a preferred embodiment of the invention the hot strip isprepared for processing and supplied as magnetic steel sheets.

It must be noted that in cases where directly used input stock isprocessed to hot strip according to the invention, particularly goodmagnetic characteristics are achieved if hot-rolling is finished in themixing region austenite/ferrite. It has been shown that in particularhot strip hot-rolled in such a way by avoiding the ferrite region issuitable for delivery to the end user without any further deformation aspart of cold-rolling.

Furthermore it has been found that a hot strip produced according to theinvention, if necessary pickled, can be used for certain applicationswithout the need for any final cold working. For special requirementswhere improved processability of the magnetic hot strip producedaccording to the invention and supplied without distinct cold-rolling,is demanded, this can be achieved in that the pickled hot strip isflattened at a degree of deformation of ≦3%. As a result of flattening,uneven areas on the surface of the strip are smoothed without therebeing any significant influence on the microstructural conditionproduced as part of hot-rolling.

As an alternative or in addition to a pure smoothing pass of the typeexplained above, apart from an improvement in surface characteristics,the magnetic characteristics of the hot-rolled strip produced accordingto the invention can also be improved in that the pickled hot strip istemper-rolled at a degree of deformation of more than 3% but 15% at themost. Again, this subsequent rolling does not bring about any typicalreduction in thickness which would be comparable to the change in stripthickness during typical cold-rolling because of the high degree ofdeformation achieved in this way. But rather, additional deformationenergy is introduced into the strip which has a positive influence onsubsequent processability of the temper-rolled strip.

The magnetic steel sheets which are supplied according to the inventionas hot strip, can be subjected to final annealing, at an annealingtemperature of ≧740° C. in the usual way before it is prepared forprocessing and delivery. By contrast, if final annealing is to becarried out at the processor's location, then a hot magnetic steel stripwhich has not been subjected to final annealing can be provided in thatprior to preparation for processing and delivery, the hot stripundergoes recrystallising annealing at annealing temperatures >650° C.to form a magnetic steel strip which has not been subjected to finalannealing.

Due to its mechanical characteristics, the hot strip produced accordingto the invention is however also particularly suited for single-stage ormulti-stage rolling in the conventional way, to a final thickness. Ifcold-rolling is carried out in a multi-stage process, at least one ofthe cold-rolling stages should be followed by intermediate annealing, soas to maintain the good mechanical characteristics of the strip.

If a fully-finished magnetic steel strip is to be produced, thencold-rolling is followed by final annealing at an annealing temperaturewhich is preferably >740° C.

By contrast, if a semi-finished magnetic steel strip is to be produced,then cold-rolling, which may have been carried out in several stages, isfollowed by recrystallising annealing in a hood-type annealing furnaceor in a continuous furnace at temperatures of at least 650° C.Subsequently, the cold-rolled and annealed magnetic steel strip islevelled and rerolled.

Cold-rolled magnetic steel strip produced according to the invention hasoutstanding cutting and stamping characteristics and as such isparticularly suitable for processing into components such as lamella orblanks. If semi-finished magnetic steel sheets are processed, it isadvantageous if the components made from such magnetic steel sheets aresubjected to final annealing at the user's location.

Irrespective of whether semi-finished or fully-finished magnetic steelsheets are produced, according to a further embodiment of the invention,final annealing of the cold-rolled magnetic steel sheets is preferablycarried out in a decarburising atmosphere.

DETAILED DESCRIPTION OF THE INVENTION

Below, the invention is explained in more detail by means of exemplaryembodiments.

Hereinafter, “J2500”, “J5000” and “J10000” designate the magneticpolarisation at magnetic field strengths of 2500 A/m, 5000 A/m and 10000A/m respectively.

“P 1.0” and “P 1.5” designate the hysteresis loss at a polarisation of1.0 T and 1.5 T respectively, at a frequency of 50 Hz.

The magnetic characteristics shown in the following tables were obtainedby measurements on individual strips, along the direction of rolling.

Table 1 lists the contents of the essential alloying constituents inweight % for three steels used for the production of magnetic steelsheets according to the invention.

TABLE 1 Steel C Si Al Mn A 0.008 0.1 0.12 0.34 B 0.008 0.33 0.25 0.81 C0.007 1.19 0.13 0.23

As an input stock, the slabs cast from steels A, B or C were reheated toa temperature exceeding 1000° C. and put though a finish-rolling linecomprising several roll stands. In the finish-rolling line, at least thefirst deformation pass was carried out exclusively in the austeniticregion.

Table 2 shows the magnetic characteristics J₂₅₀₀, J₅₀₀₀, J₁₀₀₀₀, P_(1.0)and P_(1.5) for two magnetic steel sheets B1, B2 produced from steel Aor B. Following rolling in the austenitic region, the respective hotstrip destined for the production of magnetic steel sheets B1, B2 wasfinish-rolled in the two-phase mixing region austenite/ferrite at atotal deformation ε_(h) of 66%. The rolled hot strip was then coiled ata coiling temperature of 750° C. Immediately thereafter, the coiled hotstrip was cooled and conveyed for further processing.

TABLE 2 J₂₅₀₀ J₅₀₀₀ J₁₀₀₀₀ P_(1.0) P_(1.5) Sheet [T] [T] [T] [W/kg][W/kg] B1 1.739 1.813 1.9091 3.594 7.130 B2 1.724 1.802 1.896 3.0025.959

Table 3 shows the magnetic characteristics J₂₅₀₀, J₅₀₀₀, J₁₀₀₀₀, P_(1.0)and P_(1.5) for magnetic steel sheets B3, B4 and B5. Sheet B3 wasproduced from steel A; sheet B4 from steel B, and sheet B5 from steel C.Following deformation in the austenitic region, the hot strip destinedfor the production of magnetic sheets B3, B4 and B5 was also deformedexclusively in the two-phase mixing region austenite/ferrite. The totaldeformation ε_(h) during rolling in the mixing region was 66%.Subsequently the hot strip was coiled at a temperature of 750° C.However, in a procedure which differs to that applying to the magneticsteel sheets B1, B2, the hot strip destined for the production of thesheets B3, B4, B5 was then held at the coiling temperature for at least15 minutes before being conveyed for processing into cold strip.

TABLE 3 J₂₅₀₀ J₅₀₀₀ J₁₀₀₀₀ P_(1.0) P_(1.5) Sheet [T] [T] [T] [W/kg][W/kg] B3 1.755 1.828 1.920 3.258 6.522 B4 1.737 1.812 1.909 3.075 6.101B5 1.689 1.765 1.859 2.596 5.304

Table 4 shows the magnetic characteristics J₂₅₀₀, J₅₀₀₀, J₁₀₀₀₀, P_(1.0)and P_(1.5) for magnetic steel sheets B6, B7 and B8, which sheets, inthe order stated, were also produced from steels A, B or C respectively.Following deformation in the austenitic region, the respective hot stripdestined for the production of magnetic steel sheets B6, B7 and B8 wasfinish-rolled in the two-phase mixing region austenite/ferrite. Thetotal deformation ε_(h) achieved in the two-phase mixing region was 50%.The hot strip was then subjected to several deformation passes in theferritic region. The total deformation ε_(h) achieved in the ferriticregion was less than 30%. The hot strip which was finish-rolled in sucha way was then coiled at a temperature of 750° C. Immediatelythereafter, the hot strip was cooled in the coil.

TABLE 4 J₂₅₀₀ J₅₀₀₀ P₁₀₀₀₀ J_(1.0) P_(1.5) Sheet [T] [T] [T] [W/kg][W/kg] B6 1.748 1.822 1.916 3.564 7.121 B7 1.721 1.797 1.893 2.935 5.868B8 1.709 1.791 1.884 2.630 5.246

Table 5 shows the magnetic characteristics J₂₅₀₀, J₅₀₀₀, J₁₀₀₀₀, P_(1.0)and P_(1.5) for magnetic steel sheets B9, B10 and B11. Sheet B9 wasproduced from steel A; sheet B10 from steel B, and sheet B11 from steelC. The hot strip destined for the production of magnetic sheets B9, B10and B11 was subjected to the same deformation in the finish-rollingline, as was the case with the strip destined for the production ofsheets B6, B7 and B8. The hot strip finish-rolled in this way was coiledat a temperature of 750° C. However, in a procedure which differs fromthat applying to the magnetic steel sheets B6, B7 and B8, the hot stripdestined for the production of sheets P9, B10, B11 was then held at thecoiling temperature for at least 15 minutes before being conveyed forprocessing into cold strip.

TABLE 5 J₂₅₀₀ J₅₀₀₀ P₁₀₀₀₀ J_(1.0) P_(1.5) Sheet [T] [T] [T] [W/kg][W/kg] B9  1.746 1.819 1.914 3.305 6.657 B10 1.731 1.805 1.901 2.9095.811 B11 1.690 1.765 1.858 2.587 5.304

Table 6 shows the magnetic characteristics J₂₅₀₀, J₅₀₀₀, J₁₀₀₀₀, P_(1.0)and P_(1.2) for a magnetic steel sheet B12 which was produced from steelC. After deformation in the austenitic region, the hot strip destinedfor the production of magnetic sheet B12 was deformed exclusively in thetwo-phase mixing region austenite/ferrite. The total deformation ε_(h)achieved in the two-phase mixing region was 66%. The finish-rolled hotstrip was then coiled at a temperature of less than 600° C. Immediatelythereafter, the hot strip was cooled in the coil.

TABLE 6 J₂₅₀₀ J₅₀₀₀ J₁₀₀₀₀ J_(1.0) P_(1.5) Sheet [T] [T] [T] [W/kg][W/kg] B12 1.724 1.800 1.894 2.577 5.105

Table 7 lists the contents of the essential alloying constituents inweight % for two further steels used for the production of hot stripproduced according to the invention and subsequently prepared forprocessing without distinct cold-rolling, and supplied as magnetic steelsheets.

TABLE 7 Steel C Si Al Mn C 0.008 0.10 0.12 0.34 D 0.007 1.19 0.13 0.23

Melts formed according to the compositions shown in table 7 werecontinuously cast in a casting and rolling plant to form a roughed stripwhich was continuously conveyed to a hot-roll line comprising severalroll stands. During hot-rolling of the respectively produced magneticsteel sheets C1-C3 and D1-D3, the main emphasis on deformation wascarried out in the region where the respective strip was in theaustenitic state. The last pass of hot-rolling was however carried outaccording to the invention in the mixing region austenite/ferrite. Thetotal deformation ε_(H) achieved was 40%. Subsequently the hot strip wascoiled at a temperature of 750° C.

Tables 8a-8c show the magnetic characteristics J₂₅₀₀, J₅₀₀₀, J₁₀₀₀₀,P_(1.0) and P_(1.5) for the three magnetic steel sheets C1-C3 or D1-D3produced from the steels C or D.

In the case of examples C1, D1(Table 8a), after cooling, the hot stripwas directly prepared for processing into commercially availablemagnetic steel sheets and supplied to the end user. In the case ofexamples C2, D2 (Table 8b), prior to delivery to the end user, the hotstrip was pickled and additionally subjected to a smoothing pass. Duringthis smoothing pass, a deformation ε_(H) of max. 3% was achieved. Priorto delivery, strips C3, D3 (Table 8c) were pickled and thentemper-rolled.

TABLE 8a J₂₅₀₀ J₅₀₀₀ J₁₀₀₀₀ P_(1.0) P_(1.5) Sheet [T] [T] [T] [W/kg][W/kg] C1 1.646 1.729 1.522 5.941 13.276 D1 1.642 1.716 1.548 4.0959.647

TABLE 8b J₂₅₀₀ J₅₀₀₀ J₁₀₀₀₀ P_(1.0) P_(1.5) Sheet [T] [T] [T] [W/kg][W/kg] C2 1.661 1.735 1.577 5.409 13.285 D2 1.621 1.699 1.535 3.7168.776

TABLE 8c J₂₅₀₀ J₅₀₀₀ J₁₀₀₀₀ P_(1.0) P_(1.5) Sheet [T] [T] [T] [W/kg][W/kg] C3 1.642 1.716 1.548 4.095 9.647 D3 1.608 1.686 1.529 3.023 7.447

It has been shown that the magnetic steel sheets C1-C3 or D1-D3, too,which were produced according to the invention as hot strip and as suchwere supplied to the end user without distinct cold-rolling, haveoutstanding magnetic characteristics which render them suitable, withoutfurther ado, for use in a multitude of applications.

Comparison tests were carried out on magnetic steel sheets, 1 mm inthickness, produced according to the method according to the invention,and on magnetic sheets which were hot-rolled and cold-rolled in theconventional way. These tests showed that the achievable values of themagnetic polarisation and the achievable values of the specifichysteresis losses of the magnetic steel sheets produced according to theinvention, agree within very close ranges with those values determinedfor the respective characteristics in conventionally produced magneticsteel sheets.

What is claimed is:
 1. A method for producing non grain-orientedmagnetic steel sheet comprising: producing a hot strip from an inputstock in form of cast slabs, strip, roughed strip, or thin slabs, saidinput stock being made of steel comprising in weight %: C:0.001-0.05%Si: ≦1.5% Al: ≦0.4% with Si+2 Al≦1.7% optionally up to a total of 1.5%alloying additions selected from the group consisting of P, Sn, Sb, Zr,V, Ti, N, Ni, Co, Nb and B; balance iron and inevitable impuritieswherein the input stock is hot rolled to form a hot strip directly fromthe casting heat or after preceding reheating to a reheating temperaturebetween minimum 1000° C. and maximum 1180° C. in several deformationpasses; and subsequently coiling said hot strip in a coil at a coilingtemperature; wherein at least the first deformation pass during thehot-rolling step is carried out in a austenitic region, and at least onefurther deformation pass is carried out in a two phase austenite/ferriteregion, and wherein a total deformation ε_(h) of at least 35% isachieved during the hot-rolling step in the two phase austenite/ferriteregion.
 2. The method of claim 1, wherein the total deformation ε_(h) is60% maximum.
 3. The method of claim 1, further comprising finish rollingthe hot strip exclusively in the two phase austenite/ferrite regionafter deformation in the austenitic region.
 4. The method of claim 1,wherein the total deformation ε_(h) achieved during the hot-rolling stepin the two-phase austenite/ferrite region is at least 50%.
 5. The methodof claim 1, wherein following the hot-rolling step in the two-phaseaustenite/ferrite region, at least one deformation pass is carried outin a ferritic region.
 6. The method of claim 5, wherein a totaldeformation ε_(h) achieved during hot-rolling in the ferritic region isat least 10% and at most 33%.
 7. The method of claim 1, wherein thecoiling temperature is at least 700° C.
 8. The method of claim 7,further comprising subjecting the coiled hot strip from a coiling heatto direct annealing wherein annealing time at an annealing temperatureexceeding 700° C. is at least 15 minutes.
 9. The method of claim 6,wherein the steel comprises a Si content of at least 0.7 weight %. 10.The method of claim 1, wherein the coiling temperature is less than 600°C.
 11. The method of claim 9, further comprising immediately followingcoiling, subjecting the hot strip to accelerated cooling in the coil.12. The method of claim 1, wherein during the hot-rolling step in theferritic region, at least one deformation pass is carried out with theuse of lubricant.
 13. The method of claim 12, wherein all deformationpasses taking place in the ferritic region are carried out with rolllubrication.
 14. The method of claim 1, further comprising annealing thehot strip after the coiling step at an annealing temperature of at least740° C.
 15. The method of claim 14, further comprising annealing thecoiled hot strip in a batch-type annealing furnace.
 16. The method ofclaim 14, wherein the annealing step is carried out in a continuousfurnace.
 17. The method of claim 1, wherein the thickness of the coiledhot strip is ≦1.5 mm.
 18. The method of claim 1, further comprisingpreparing the hot strip for further processing and supplying saidprocessed hot strip as magnetic steel sheets.
 19. The method of claim18, further comprising planishing the hot strip at a degree ofdeformation of ≦3% prior preparation for the processing and thesupplying steps.
 20. The method of claim 18, further comprising temperrolling the hot strip at a degree of deformation of >3-15% prior thepreparation for the processing and the supplying steps.
 21. The methodof claim 18, further comprising subjecting the hot strip to finalannealing, at an annealing temperature of >740° C. prior the preparationfor the processing and the supplying steps.
 22. The method of claim 18,further comprising prior to preparation for processing and deliverysubjecting the hot strip to recrystallising annealing at annealingtemperatures >650° C. to form a magnetic steel strip which has not beensubjected to final annealing.
 23. The method of claim 16, furthercomprising cold rolling the hot strip in single-stage or multi-stagerolling, to a final thickness.
 24. The method of claim 23, furthercomprising cold rolling the hot strip in several stages wherein at leastone of the cold-rolling stages is followed by intermediate annealing.25. The method of claim 23, further comprising subjecting the cold stripto final annealing following cold rolling, said final annealing takingplace at an annealing temperature of >740° C.
 26. The method of claim23, wherein following the cold-rolling step, the cold strip is subjectedto recrystallising annealing in a batch-type annealing furnace or in acontinuous furnace at annealing temperature of at least 650° C. to forma magnetic steel strip which has not been subjected to final annealing,said cold strip being subsequently leveled and rerolled.
 27. The methodof claim 26, wherein the annealing step is carried out in adecarburising atmosphere.
 28. The method of claim 1, wherein the steelcomprises up to a total of 1.5% of alloying additions selected from thegroup consisting of P, Sn, Sb, Zr, V, Ti, N, Ni, Co, Nb or B.
 29. Themethod of claim 1, wherein the coiling temperature is less than 550° C.30. The method of claim 8 further comprising cold rolling the hot stripin single-stage or multi-stage rolling, to a final thickness.
 31. Themethod of claim 30, further comprising cold rolling the hot strip inseveral stages wherein at least one of the cold-rolling stages isfollowed by intermediate annealing.
 32. The method of claim 30, furthercomprising subjecting the cold strip to final annealing following coldrolling, said final annealing taking place at an annealing temperatureof >740° C.
 33. The method of claim 30, wherein following thecold-rolling step the cold strip is subjected to recrystallisingannealing in a batch-type annealing furnace or in a continuous furnaceat annealing temperature of at least 650° C. to form a magnetic steelstrip which has not been subjected to final annealing, said cold stripbeing subsequently leveled and rerolled.
 34. The method of claim 33wherein the annealing step is carried out in a decarburising atmosphere.35. The method of claim 11 further comprising cold rolling the hot stripin single-stage or multi-stage rolling, to a final thickness.
 36. Themethod of claim 35, further comprising cold rolling the hot strip inseveral stages wherein at least one of the cold-rolling stages isfollowed by intermediate annealing.
 37. The method of claim 35, furthercomprising subjecting the cold strip to final annealing following coldrolling, said final annealing taking place at an annealing temperatureof >740° C.
 38. The method of claim 35, wherein following thecold-rolling step the cold strip is subjected to recrystallisingannealing in a batch-type annealing furnace or in a continuous furnaceat annealing temperature of at least 650° C. to form a magnetic steelstrip which has not been subjected to final annealing, said cold stripbeing subsequently leveled and rerolled.
 39. The method-of claim 35wherein the annealing step is carried out in a decarburising atmosphere.40. The method of claim 14 further comprising cold rolling the hot stripin single-stage or multi-stage rolling, to a final thickness.
 41. Themethod of claim 40, further comprising cold rolling-the hot strip inseveral stages wherein at least one of the cold-rolling stages isfollowed by intermediate annealing.
 42. The method of claim 40, furthercomprising subjecting the cold strip to final annealing following coldrolling, said final annealing taking place at an annealing temperatureof >740° C.
 43. The method of claim 40, wherein following thecold-rolling step the cold strip is subjected to recrystallisingannealing in a batch-type annealing furnace or in a continuous furnaceat annealing temperature of at least 650° C. to form a magnetic steelstrip which has not been subjected to final annealing, said cold stripbeing subsequently leveled and rerolled.
 44. The method-of claim 40wherein the annealing step is carried out in a decarburising atmosphere.